The defensive trio that had enjoyed so much success together had been apart since the announcement of Shaw's eight-week suspension for gambling on football.
Not long after Shaw was outed, Maxwell went down with a broken thumb, costing him the last three rounds of the home and away season.
Both stars returned for the Magpies' 20-point qualifying final win over West Coast on Saturday, and O'Brien couldn't have been happier.
"We've played maybe 130 games together, we've got such great chemistry, and I just love playing with those guys," O'Brien told collingwoodfc.com.au after the victory, which moved Collingwood into its fourth straight preliminary final.
"They put their bodies on the line for me."
O'Brien was close to best on ground, collecting 30 disposals and continually driving the Magpies from half-back to half-forward with his bursting runs and long, line-breaking kicks.
Shaw's contribution wasn't far behind. He also amassed 30 disposals and, along with Leon Davis, was his team's best rebounder from defensive 50.
Shaw's ability to have an immediate impact after two months on the sidelines was no surprise to O'Brien.
"It's to be expected," he said.
"Heath's the type of guy that's always going to find the footy.
"He's just a natural; it's in his blood."
But the 24-year-old saved his highest praise for his captain, who spent much of the afternoon minding West Coast's resting ruckman - either Nic Naitanui or Dean Cox.
Maxwell's form had been questioned at times during his injury-interrupted 2011 season, which made O'Brien all the more pleased to see him perform well.
"He cops so much criticism, and I'm his number one supporter because I know from playing alongside him how hard he goes about it, and how much he makes me and the rest of our teammates better players," O'Brien said.
With key defender Ben Reid missing, O'Brien said the Magpies' plan to subdue the Eagles' tall forwards was based on supporting each other at contests wherever possible.
It worked, with Quinten Lynch, Josh Kennedy, Jack Darling, Cox and Naitanui combining for only six goals.
"We wanted to try and limit the one-on-ones, make it a two-on-one and help each other out in the air," O'Brien said.
"I think we were effective in that, and I don't think their big guys had as much influence as they could have in the air."
That said, O'Brien liked what he saw in the Eagles' athletic young ruckman Naitanui, who had 31 hit-outs, eight clearances, and drove the ball inside attacking 50 six times.
"Naitanui's an absolute freak," O'Brien said.
"He could be the best player to ever have played this game if he keeps going the way he is."
